S80T6 High pitch whistle @ idle

[Laserowl]

Just started to notice a whistle like noice at idle on the T6.
Dissapears on acceleration but is there as soon as you take foot of accelerator. No obvious signs of air / vaccum leaks, performance is ok.
I did think maybe PCV firetrap/ pipework but removing filler cap makes no diffrence. Also its intermitent so is confusing if it is a leak.


Any ideas anyone, its driving me mad.

[LeeT5]

At idle....sounds like its more of a sqeal than a whistle. You sure its not you AUX belt slipping? Spray a little bit of WD on the belt at idle just to eliminate the belt. Could save you a lot of stress.

Other than that, can't help you. Impossible to say without seeing the car in the flesh.